rt

#include <bits/stdc++.h>
using namespace std;
const int N=50;
int dp[N][N];
string A,B;
int main() 
{
    cin>>A>>B;
    int n=A.size()-1;
	int m=B.size()-1; 
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=m;j++)
		{
			if(A[i]!=B[j])
			dp[i][j]=max(dp[i][j-1],dp[i-1][j]);
			else 
			dp[i][j]=dp[i-1][j-1]+1;	
		}
	}
	cout<<dp[n][m]<<endl;
	string lcs;
    int i=n,j=m;
    while (i>0&&j>0) 
	{
        if(A[i]==B[j])
		{
            lcs=A[i]+lcs;
            i--;
            j--;
        } 
		else if(dp[i-1][j]>dp[i][j-1]) i--;
		else j--;
    }
    cout<<lcs;
	return 0;
}